The VI setting is analogue which is what it is currently set too. The other option is VR which is the POT but I can give removing the link it a go if you like.
I agree the frequency is the problem but the 9000 comes not from noise but because that is the speed it was left at on the previous test.
I just closed down and reopened UCCNC again which would have resent the speed info to the VFD and I'm sure it did.
I just think my VFD is not reading it properly. Some sort of communication error
I am thinking of trying different baud rates and parities to see if it helps in any way.
I really think the plugin is good and it is just something here that is causing the issue. Hopefully the RS485 adapter.
I would imagine noise would not be an issue until the spindle starts. I have everything else turned off in the workshop. Once the spindle starts all bets are off.
I will try everything I can think of and let you know how I get on.
I'm sure it isn't the plugin.
Cheers
Peter